Veging

Hello could some one please advice me when it is time to put lights on 12 hour cycle i have 5 plants that have been growing for 9 weeks now on 18 hour cycle however am uncertain of when and how to top them though i have noticed different sort of crown leaves recentley but how do i know when they r flowering they just seem to be growing and growing but no buds or anything does one induce them to flower by changing the lighting hours?
Thank you for any advice available

you force flowering by changing light cycle to 12/12.

they are ready to flower when they are between 12-18 inches tall with alternating nodes.

got pics?

Hi what do u mean by alternating nodes?

when ur nodes grow seperatly and how much space do u have like the height of ur grow room im pretty sure ur plant are about 3ft tall right now right??? and yeah like burlingo said switch the times to 12/12 and ur planmt will go into flowering and what he means by alternating nodes is bothe nodes dont grow at the same time its one than the other and nodes are where ur branches come out of the main stem and here goes a link of how to TOP/FIM by the great moogie Fimming and Topping 101

Yeah man like noob grower said.jsut switch the lights to 12 on 12 off. and you can change it whenever oyu want to bro.some people do it straight from seed when height is an issue. but yeah man like do it now if you want to.they grow more when you put em in flowering so do it based on oyur height limits...and post pics!